The suspension for heavy vehicles, including trucks and trailers, is typically supported with leaf springs and beam suspensions. Beam suspension and leaf springs are positioned between an axle, or axle assembly, and the load carrying frame. Beams and leaf springs are normally terminated at each of two ends with a circular eyelet. A bushing passes though the eyelet and connects at bushing pin ends to a hanger or other structure secured to the vehicle frame. The bushing includes an annular elastomeric element (rubber or polyurethane) about the pin to provide some vibration isolation and permit some limited rotation at the eyelet.
As an example, leaf springs are manufactured of spring steel and, over time, rust can form between the eyelet and the bushing, causing difficulty during eventual replacement. In highway trailer axle assemblies, which operate in severe conditions, bushings can require replacement at frequent intervals.
Applicant's experience has been that bushing replacement, such as that for suspensions including a variety of Henrickson suspension (Hendrickson Truck Systems Group, Woodridge, Ill., USA), can require removal of the suspension and use of a hydraulic press, typically found in a service shop environment, to force the bushing from the eyelet.
For example, refurbishing of bushings for a tri-axle trailer entails: removal of the six leaf springs, press removal of the bushings, installation of a new bushings and reinstallation of the six leaf springs on the trailer. This operation can take as much as 6 to 8 hours and require access to a shop press.